1. Field of the Invention
The present disclosure relates to an integrated hybrid heat exchanger for a hybrid vehicle. More particularly, it relates to an integrated hybrid heat exchanger using a water head difference, in which an electrical component cooling system and an internal combustion engine cooling system are integrated into a single cooling system such that bubbles generated in the cooling system during operation can be easily removed, thereby improving cooling efficiency.
2. Description of Related Art
In general, a hybrid vehicle is a vehicle that is equipped with an internal combustion engine and a motor such that the vehicle is driven by one or both of the engine and the motor.
The hybrid vehicle is driven by the motor during initial driving or during cruise driving and is driven by the internal combustion engine during uphill driving or during battery discharge, thus improving fuel efficiency.
Here, since electrical components including the motor generate heat during operation, it is necessary to provide a cooling system that prevents an increase in the temperature of the components in order to maintain the input and output characteristics of the components at an optimum state.
Especially, in the case of a battery, it is necessary to maintain an optimum temperature in order to maintain the overall charge-discharge efficiency at its best.
Accordingly, the heat generated during the charge and discharge of the battery is cooled to the optimum temperature using the cooling system.
For example, when the hybrid vehicle is driven by the motor, heat is generated by a phase shift of current (AC to DC) in an inverter, and heat is also generated during operation of the motor and an electric generator. In order to cool these electrical components, the hybrid vehicle includes an electrical component cooling system in which cooling water is circulated through an electric pump→the inverter→an inverter reservoir tank→a radiator during operation of the motor.
Accordingly, a hybrid cooling system is operated by two cooling systems including the electrical component cooling system and an internal combustion engine cooling system.
In this hybrid cooling system, the internal pressures of an integrated radiator, in which individual radiators are hydraulically isolated from fluid communication with each other, may be different from each other according to the operation of the internal combustion engine and the electric motor, the flow rate of a water pump, and the temperature of coolant. In this case, the dynamic pressures may be different from each other even if the total pressures are the same.
Recently, an integrated cooling system, in which the electrical component cooling system and the internal combustion engine cooling system are integrated into a single cooling system so as to provide an improvement in cooling efficiency, an advantage of layout design, a reduction in the number of components, and a reduction in manufacturing cost, is proposed.
For example, Japanese Patent Publication No. 1998-259721 and U.S. Pat. No. 6,124,644 disclose cooling systems, in which an existing internal combustion engine radiator is divided into a radiator for an internal combustion engine and a radiator for electrical components.
However, in the case of the cooling system disclosed in Japanese Patent Publication No. 1998-259721, bubbles formed in the radiator for the electrical components are collected at the top of a tank; however, since an outlet for discharging the collected bubbles is situated at the bottom, it is difficult to remove the collected bubbles from the tank, thus deteriorating the cooling efficiency.
Moreover, the temperature and pressure of the radiator for the internal combustion engine and the radiator for the electrical components are set to be different from each other in the above cooling system and, therefore, if an excess pressure is generated in one of the radiator for the internal combustion engine and the radiator for the electrical components, the pressure difference between the two radiators causes core deformation and fatigue failure, thus reducing the durability.
In the case of the cooling system disclosed in U.S. Pat. No. 6,124,644, in which bubbles collected at an upper tank of the radiator are removed only when the radiator cap is opened, since the tank of the radiator for the electrical components has a size smaller than the radiator for the internal combustion engine, the space for collecting bubbles is insufficient, which restricts the coolant flow, thus deteriorating the cooling efficiency.
Moreover, the temperature and pressure of the radiator for the internal combustion engine and the radiator for the electrical components are also set to be different from each other in this cooling system and, therefore, if an excess pressure is generated in one of the radiator for the internal combustion engine and the radiator for the electrical components, the pressure difference between the two radiators causes core deformation and fatigue failure, thus reducing the durability.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.